[uClinux-dev] append trailer to frames in fec?

[cg]

Hi to all,

my mcf5329 on a custom board is connected to a 8 port switch ic via mii. 
I want to realize a proprietary protocol where i send frames out of 
targeted ports. The switch offers a trailer mode to send out of targeted 
ports. You just have to append 4 byte to the frame and the switch knows 
which port to send from. The switch also cuts this 4 byte long trailer 
and calculates a knew fcs/crc, so the frames are normal for the rest of 
the network.
I have no problem with directing the frames in the protocol. The frames 
leave from the right port and in the shape they should. But i am in 
trouble because of the frames send by my web management running on boa, 
ping replies and so on are not send.

The frames are destroyed because the switch cuts the last four bytes and 
there is no useful transmission. So i tried to fix it by increasing the 
data space in sk_buff with skb_put(skb, 4). Unfortunately it did not 
work. Sometimes i also got kernel panics because the tail pointer was 
passing the end pointer. I am really stuck at the moment and don´t know 
how to go on.
Another thing i thought of is to change the "frame creation" in boa and 
icmp, but i will probably always forget some application that transmits 
frames. So i think it is better to solve it global.
Can anybody give me a hint how and where to solve this problem? I have 
never been so deep in the kernel source.

Thank you for any help

Chris